**Acknowledgement**

For providing technical support and access to the in-house and synchrotron X-ray sources we are thankful to Aiping Dong of the Toronto Structural Genomics Consortium and the IMCA-CAT staff at the APS, respectively. We also extend our gratitude to Dr. Tara Davis for providing bacterial cell cultures for purification of EphA3, Kathy Jones for her help with initial crystallization experiments, Joe Miller for help with business development and Jason C. Ellis for machining accessory items. Use of the IMCA-CAT beamline 17-ID at the Advanced Photon Source was supported by the companies of the Industrial Macromolecular Crystallography Association through a contract with the Hauptman-Woodward Medical Research Institute. Use of the Advanced Photon Source was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, contract No. DE-AC02-06CH11357.
